Apparatus for silicon epitaxial chemical vapor deposition of substrates, for example of silicon wafers, is known. Generally speaking, such apparatus utilizes a cold wall. The walls of such apparatus are hundreds of degrees cooler than the reaction temperature, and the energy that is lost by radiation through them is often on the order of about 32 watts per square cm. at 1200 degrees C. In order to keep cold walled reactor walls cool they have to radiate heat. This energy loss must continually be made up to sustain deposition, and it represents a substantial element of cost. The energy conversion efficiency of the heating means in cold wall reactors is in the area of 50%. These conversion losses also add to power cost.
Accordingly, this invention has an objective to provide apparatus with substantially greater productivity and substantially lower energy requirement. Compared to many conventional machines, the apparatus of this invention has per unit time about 5 times the productivity, and utilizes less than 20% of the energy per unit output. The reaction chamber can accommodate more wafers. It requires less energy because radiation from the system is repressed.
It is an object of this invention to utilize apparatus having a hot wall, wherein the energy loss is by inefficiency of the insulation, which is minimal, and the end losses into the reactor base.
Also, in the treatment of single crystalline substrates, uniformity of heating and cooling across the crystal is essential, because if it exceeds a relatively small tolerance, slip will occur within the crystal planes. This crystalagraphic slippage renders useless the area where it occurs. It is an object of this invention to provide apparatus wherein the system can be operated at high throughputs and efficiencies, and in which deposition parameters can be substantially improved.